Coated bituminized fiber pipe



United States Patent 3,039,495 COATED BITUMINIZED FIBER PIPE John J. Drukker, Wyckolf, N.J., assignor to The Patent and Licensing Corporation, New York, N.Y., a corporation of Massachusetts No Drawing. Filed Feb. 23, 1960, Ser. No. 10,093

. 3 Claims. (Cl. 138145) v This invention relates to a coated bituminized fiber pipe or conduit and more particularly the invention is concerned with the application of a special type of bituminized coating to a bituminized fiber pipe in order to make the pipe cleaner to handle.

Bituminized fiber pipe or conduits are a well known product employed primarily for conducting water and drainage and for carrying electrical cables and the like where resistance to corrosion, erosion and disintegration is required. The pipe is composed of a bituminous compound reinforced with an interwoven fibrous structure. Usually it is a pipe made on a specialized paper machine from wood fiber which pipe is subsequently impregnated with coal tar pitch. Its nature and characteristics are fully disclosed in the pamphlet entitled Commercial Standard CSl16-54 issued by the United States Department of Commerce and having an effective date of September 10, 1954.

For best results in resistance to underground deterioration this pipe is impregnated with a molten tar pitch during its manufacture. This coal tar pitch material has very excellent properties for the purpose, but has the disadvantages that it is brittle and hence tends to flake off when handled. In addition, coal tar pitch is somewhat irritating to the skin of certain people.

It is therefore an object of the present invention to provide an improved bituminized fiber pipe having a cleaner surface.

It is a further object of the present invention to provide an improved coated bituminized fiber pipe whose outer surface is non-irritating.

Itis a further object of the present invention to provide an improved coated bituminized fiber pipe having a coating thereon which makes the pipe cleaner and nonirritating by means of a coating which is compatible and inexpensive.

These and other objects are attained by the present invention which relates to a coal tar pitch impregnated fiber pipe having on the outside surface thereof a coating of a dried film of a combination clay and soap type asphalt emulsion.

This coating is preferably used with additional filler. A filled hot asphalt is not suitable since temperatures sufficient-ly high to apply such a coating would melt the coal tar pitch. The combination clay and soap type asphalt emulsions give a coating which is easily applied at reasonably low temperatures, is not tacky at outdoor temperatures which may reach 160 F., is compatible with or wets the coal tar pitch surface of the pipe and is water and abrasive resistant. The coating prevents pitchburn, reduces fragility and reduces dusting and is thus cleaner.

Example A standard coal tar pitch impregnated fiber pipe was coated with the following composition: 40 parts by weight of a 64% solids asphalt emulsion No. 1, 6.53 parts 58% solids asphalt Emulsion No. 2, 25.6 parts slate flour, 2.0 parts Dixie clay, 0.001 part sodium dioctyl sulfo succinate, 25.87 parts water.

The procedure to make the coating composition involves putting 90% of the water in a mixing vessel, adding the slate flour while mixing and subsequently mixing in the Emulsion No. l and subsequently the Dixie clay in ice a slurry in the rest of the water. The mixer is stopped and the Emulsion No. 2 added and the mixing continued for a short period of time. The sodium dioctyl sulfo succinate is then added to reduce the viscosity. In the event that the mixture is too viscous for a coating composition, further water may be mixed in to yield a viscosity of approximately 1300-1600 c.p.s. Care should be taken to avoid aeration or foaming so the material may be applied as a thin film without breaks. The film is coated on bituminized fiber pipe by any means such as spraying or rotating the pipe in a shallow bath of coating. Preferably, however, rolling the pipe on a felt or belt saturated or coated with the coating composition applies the coating evenly to various sized pieces of pipe. Subsequently the pipe is dried preferably by the use of heat.

In the above example, Emulsion No. 1 is made with an asphalt having a softening point of 185 F. and 10-12 penetration at 77 F. The emulsion contains about 64 parts asphalt, 33.5 parts Water, 2.5 parts bentonite 0.06 part potassium bichromate and 0.08 part pyrogallic acid.

Emulsion No. 2 is made with an asphalt having a softening point of -l30 F. and a penetration of 51-60 at 77 F. It contains Vinsol resin (petroleum hydrocarbon insoluble residue from pinewood rosin) and potassium hydroxide in the proportions 56 parts asphalt, 2 parts Vinsol, 0.5 part potassium hydroxide together with 41 parts water.

The above ingredients may be varied to some extent but in general the composition should include a clay type asphalt emulsion in the range 20-60% of the composition, a soap type asphalt emulsion in the range 5-10% of the composition, filler in the range 10-40% of the composition and added water in the range 10-40% of the composition, the amount of water being adjusted to produce a coating suitable for application.

It may also be desirable to add 12% of carbon black in a water dispersion to the coating to give a darker color and further improve weathering resistance. It may also be desirable to add a small amount such as 2% of a fine asbestos to the final coating composition to further increase weathering properties.

The coating prevents dusting of the coal tar pitch bituminized fiber pipe which dusting might otherwise occur during handling and shipping. Pitch dust is a skin irritant, and some people are particularly subject to skin irritations from this. The coating has good weathering performance as required since the pipe is often stored out of doors for long periods of time before use. The material is non-tacky for handling at elevated temperatures, as for example, F. The coating after setting by evaporation of water is non-susceptible to moisture as shown by a soaking test for 24 hours followed by vigorous rubbing of the coating. The coating is stable in storage with a minimum of settlement, and is capable of being pumped. All of the desirable features are met sirnultaneously by this inexpensive coating.

The clay type emulsion (Emulsion No. 1) is preferably made with an asphalt having a softening point in the range 160-200 F. while the soap type emulsion (Emulsion No. 2) may be made with an asphalt having a softening point in the range 120-140 F. It will be understood that other clays or soaps other than Vinsol soaps may be used as emulsifying agents. In the coating composition itself the filler which in the example is slate flour may be any one of a large number of fillers commonly used in asphalt emulsion compositions including asbestos, clay, whiting, silica, etc. Slate flour is preferred because of its dark color. The filler should preferably pass a 425 mesh screen to minimize settling from the emulsion in storage.

Instead of Dixie clay in the above example, a lime and bentonite slurry may be used containing for example 7% lime and 3% bentonite. The Dixie clay which is a lime bearing clay or the bentonite plus lime develops a thixotropic property such that in utilizing high solids clay type asphalt emulsions a thixotropic gel forms sufficient to suspend heavy fillers in the coating even When partially diluted with water.

The amount of water and the temperature of the coating is adjusted as Will be understood by those skilled in the art to be applied in a relatively thin film, as for example, in the range 300-1500 sq. ft. of pipe surface per gallon of coating. The heavier coatings may be used but are not necessary to the purposes of the invention and reduce the drying time.

While the bituminized fiber pipe has been described as a wood fiber product it may be a wood fiber derivative, as for example, repulped newsprint and may even contain' other types of fiber such as rag, bagasse, or the like. The pipe is ordinarily made on a special paper machine such that it is an integral product rather than a laminated product. During the impregnation with coal tar pitch, substantial amounts of pitch remain on the surface of the pipe such that the pipe may be said to be coated With coal tar pitch. The coating composition of the present invention is applied outside of and in addition to any coal tar pitch coating.

We claim:

1. An improved bituminized fiber pipe comprising fiber impregnated with coal tar pitch and having on the outer surface thereof a coating of a dried film of a mixture of a clay type asphalt emulsion and a soap type asphalt emulsion.

2. An improved bituminized fiber pipe comprising fiber impregnated with coal tar pitch and having on the outer surface thereof a coating of a dried film of a mixture of a clay type asphalt emulsion and a soap type asphalt emulsion and a filler.

3. An improved bituminized fiber pipe having a clean, non-irritating peripheral surface comprising a cellulosic fiber pipe impregnated with coal tar pitch and having on the said peripheral surface a relatively thin coating of a dried film of a mixture of clay type asphalt emulsion and soap type asphalt emulsion.

References Cited in the file of this patent UNITED STATES PATENTS 1,235,671 Fay Aug. 7, 1917 1,316,591 Perry Sept. 23, 1919 1,582,084 Richter Apr. 27, 1926 1,678,980 Gardiner July 31, 1928 

3. AN IMPROVED BITUMINIZED FIBER PIPE HAVING A CLEAN, NON-IRRITAITNG PERIPHERAL SURFACE COMPRISING A CELLULOSIC FIBER PIPE IMPREGNATED WITH COLAR TAR PITCH AND HAVING ON THE SAME PERIPHERAL SURFACE A RELATIVELY THIN COATING OF A DRIED FILM OF A MIXTURE OF CLAY TYPE ASPHALT EMULSION AND SOAP TYPE ASPHALT EMULSION. 